From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EBB60C433ED for ; Thu, 20 May 2021 00:08:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C3F5861074 for ; Thu, 20 May 2021 00:08:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229808AbhETAJ0 (ORCPT ); Wed, 19 May 2021 20:09:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:49802 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229498AbhETAJX (ORCPT ); Wed, 19 May 2021 20:09:23 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 2288E61074; Thu, 20 May 2021 00:08:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1621469283; bh=f3uW/vXpyk7s7uTXVpnaV4B91FgG/Qp7j2U1ILb43tQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=P0uIULPvkqznT4s4V72i3eF28RKp2xQBcRElIYs3WDevWUcPirbR6iSxBYrPhWmK1 7rhhHeY73aC/UCsjBZhvmTKiLAu2sv1L+Lp5I4U/oKGWmWM7OcgXNct1sXPDEE8xxK C75K6rRS8TL+cTDm/FbynSwrzt3s73+Z1fZCCPiDiFy1YLi05gUq+FWcrJaLYu2E1L 8+3gCMEW6xRb0IViK6NMen7e2bApGbzRiVl0qLV4Bc7usczCVgxpHbIUc/bt82ZrC/ 5LTiVubyyk/bhm+NS3xqBSiGln+LHPsjGlHRETYORu1vYOSu6xP/la+BbCdanbEtPc hAefqKJwiVqAg== Date: Wed, 19 May 2021 17:08:02 -0700 From: "Darrick J. Wong" To: Dave Chinner Cc: xfs , hsiangkao@aol.com Subject: Re: regressions in xfs/168? Message-ID: <20210520000802.GV9675@magnolia> References: <20210519210205.GT9675@magnolia> <20210519222006.GA664593@dread.disaster.area> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210519222006.GA664593@dread.disaster.area> Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Thu, May 20, 2021 at 08:20:06AM +1000, Dave Chinner wrote: > On Wed, May 19, 2021 at 02:02:05PM -0700, Darrick J. Wong wrote: > > Hm. Does anyone /else/ see failures with the new test xfs/168 (the fs > > shrink tests) on a 1k blocksize? It looks as though we shrink the AG so > > small that we trip the assert at the end of xfs_ag_resv_init that checks > > that the reservations for an AG don't exceed the free space in that AG, > > but tripping that doesn't return any error code, so xfs_ag_shrink_space > > commits the new fs size and presses on with even more shrinking until > > we've depleted AG 1 so thoroughly that the fs won't mount anymore. > > Yup, now that I've got the latest fstests I see that failure, too. > > [58972.431760] Call Trace: > [58972.432467] xfs_ag_resv_init+0x1d3/0x240 > [58972.433611] xfs_ag_shrink_space+0x1bf/0x360 > [58972.434801] xfs_growfs_data+0x413/0x640 > [58972.435894] xfs_file_ioctl+0x32f/0xd30 > [58972.439289] __x64_sys_ioctl+0x8e/0xc0 > [58972.440337] do_syscall_64+0x3a/0x70 > [58972.441347] entry_SYSCALL_64_after_hwframe+0x44/0xae > [58972.442741] RIP: 0033:0x7f7021755d87 > > > At a bare minimum we probably need to check the same thing the assert > > does and bail out of the shrink; or maybe we just need to create a > > function to adjust an AG's reservation to make that function less > > complicated. > > So if I'm reading xfs_ag_shrink_space() correctly, it doesn't > check what the new reservation will be and so it's purely looking at > whether the physical range can be freed or not? And when freeing > that physical range results in less free space in the AG than the > reservation requires, we pop an assert failure rather than failing > the reservation and undoing the shrink like the code is supposed to > do? Yes. I've wondered for a while now if that assert in xfs_ag_resv_init should get turned into an ENOSPC return so that callers can decide what they want to do with it. --D > IOWs, the problem is the ASSERT firing on debug kernels, not the > actual shrink code that does handle this reservation ENOSPC error > case properly? i.e. we've got something like an uncaught overflow > in xfs_ag_resv_init() that is tripping the assert? (e.g. used > > ask) > > So I'm not sure that the problem is the shrink code here - it should > undo a reservation failure just fine, but the reservation code is > failing before we get there on a debug kernel... > > Cheers, > > Dave. > -- > Dave Chinner > david@fromorbit.com